Update pyembed.c code to not have deprecation warnings on PyEval_InitThreads

[ndjensen]

When building Jep 4.0 with Python 3.10, the following warning is produced:

src/main/c/Jep/pyembed.c: In function ‘pyembed_startup’:
src/main/c/Jep/pyembed.c:398:5: warning: ‘PyEval_InitThreads’ is deprecated [-Wdeprecated-declarations]
     PyEval_InitThreads();
     ^~~~~~~~~~~~~~~~~~
In file included from /usr/local/include/python3.10/Python.h:144,
                 from src/main/c/Include/jep_platform.h:35,
                 from src/main/c/Include/Jep.h:35,
                 from src/main/c/Jep/pyembed.c:44:
/usr/local/include/python3.10/ceval.h:122:37: note: declared here
 Py_DEPRECATED(3.9) PyAPI_FUNC(void) PyEval_InitThreads(void);
                                     ^~~~~~~~~~~~~~~~~~

The documentation also points this out: https://docs.python.org/3/c-api/init.html#c.PyEval_InitThreads

Update the code to not have the deprecation warning with newer versions of Python. This may require the use of macros like #IF PY_MINOR_VERSION > 8 depending on how old of versions of Python we're supporting, I'm not sure.

The documentation says this method will be removed in Python 3.11 so this should be targeted for Jep 4.1.0 at the latest or 4.0.x if there is an earlier release.

[ndjensen]

Fix is here: https://github.com/ninia/jep/commit/0866d0a85554a0b9af372c549db571a66f524082

[ndjensen]

This is part of the 4.0.1 release.